This book was written by Leon Trotsky at the height of the Russian Civil War. While it is a polemical response to German social-democrat Karl Kautsky, it is also represents the Bolshevik defense of the extraordinary means the young workers’ republic had to take in order to defend itself from the almost two dozen armies that were on its soil trying to turn back the revolution. We have kept true to the form of the style of English used in this edition of the book, making only some spelling corrections and, of course, using the contemporary title, Terrorism or Communism.